seem to work well, after the setup my default voltages are
1.85v mem
1.30v gpu

I had some problems with the vrzone ones though, they suggested 500ohm vr multiturn trimpot between the gpu point and ground, that took my resistance from 470ish to 330, and if my calcuations are right, and i turned on my card, my voltage would of been 2.2v into vgpu,

i ended up using the 500ohm vr trimpot (for fine adjustments), 10k vr trimpot, and 370ohm resistor in series to achieve the original 470 ohms, and i trim down from there to raise my gpu voltage,

so anyone thats doing vmods on the 8800 just beware you might require higher impedence resistors across the vgpu point or KABOOM!